1. Field of Invention
The present invention relates generally to an organic-solvent vapor adsorbing apparatus for obtaining clean air by removing organic-solvent vapor from air which contains organic-solvent vapor.
2. Description of Related Art
In various factories, working places, and the like, where it is impossible to completely prevent an organic solvent from evaporating and diffusing into the air, it is necessary to constantly carry out forced ventilation or effect cleaning treatment by collecting air containing the organic-solvent vapor. In particular, if the amount of vaporized organic solvent is large, such cleaning treatments are indispensable for the purposes of securing worker safety and preventing the deterioration of the surrounding environment.
Various adsorbents and adsorbing apparatuses have hitherto been employed for removing organic solvents from air containing organic-solvent vapor or for collecting vaporized organic solvent. For example, International Patent Laid-Open No. 91/16971 discloses a rotary organic-solvent vapor adsorbing apparatus comprising a honeycomb-structure rotor that carries an adsorbent which displays the property of adsorbing organic-solvent vapor better than steam. This conventional apparatus is suitable for efficiently treating air containing a low concentration of organic-solvent vapor.
As shown in FIG. 1, this conventional rotary adsorbing apparatus comprises a honeycomb-structure rotor 1 in which a corrugated sheet and a noncorrugated sheet made of ceramic fibers or the like are superposed one on top of the other and are wound to form a roll. The apparatus further comprises an adsorbent which is carried in the rotor 1 and is rotated by setting the center of winding as an axis of rotation. Tubular draft passages formed by the shaped sheet extend in the longitudinal direction of the rotor 1. When air to be treated A is sent into these passages by a first blower F.sub.1, the organic-solvent vapor therein is adsorbed by the adsorbent in the rotor 1, and cleaned air a is discharged from the opposite side. However, the air to be treated A is not supplied to all of the draft passages of the rotor 1. Instead, a separator 3 is disposed in the vicinity of an end face 2 where the draft passages of the rotor 1 are open (another separator is coaxially disposed on the other end face as well) to form a fan-shaped treatment zone 5 and regeneration zone 4. The air to be treated A is passed through the treatment zone 5. A second blower F.sub.2 supplies regenerating heated air R along a direction opposite to the air to be treated A and into the regeneration zone 4.
As the air to be treated A is passed through the treatment zone 5, the adsorbent in the rotor 1 adsorbs organic solvent therefrom. The continuous rotational movement of the rotor 1 displaces the adsorbent and the adsorbed organic solvent therein into the regeneration zone 4. The regenerating air R heats the adsorbent while in the regeneration zone 4, thereby causing the organic solvent to be desorbed from the adsorbent. Reproduced exhaust air S containing the desorbed organic-solvent vapor is exhausted from the opposite end face of the rotor 1. In this manner, the adsorbent is constantly regenerated in the regeneration zone 4 before the rotational movement of the rotor 1 returns the adsorbent back to the treatment zone 5.
However, in the above-described conventional rotary organic-solvent vapor adsorbing apparatus, the rotor 1 and adsorbent therein possess a high temperature immediately after leaving the regeneration zone 4 and entering the treatment zone 5. The adsorbent's ability to adsorb the solvent vapor is inhibited at such high temperatures. As the rotor 1 and adsorbent therein are continuously rotated through the treatment zone 5 by the rotational movement of the rotor 1, they are eventually cooled by the air to be treated A which flows into the treatment zone 5. Unfortunately, the rate at which the air to be treated A decreases the temperature of the adsorbent is insufficient. The adsorbent only gradually begins to exhibit its adsorbing capabilities as it rotates through the treatment zone 5. For this reason, part of the solvent vapor contained in the air to be treated A passes through the treatment zone 5 without being adsorbed. The operational efficiency of the conventional apparatus is thus limited.
The present invention attempts to overcome this problem by providing an organic-solvent vapor adsorbing apparatus for removing organic-solvent vapor in air that includes a rotor in which tubular draft passages of a honeycomb-structure are arranged in a direction of a rotational axis. An adsorbent for adsorbing organic-solvent vapor is contained in the rotor. The rotor is rotated by a rotatively driving means.
A pair of separators partitions a vicinity of each of the end faces of the rotor and divides the rotor into three wedge-shaped zones. The separators are plate-like members disposed in face-to-face relation to the ends of the rotor and are axially arranged. The three wedge-shaped zones include a treatment zone, a regeneration zone, and a purge zone.
A first air-blowing means is provided for supplying air to be treated to the treatment zone. The adsorbent adsorbs the organic-solvent vapor from the supplied stream of air, so that treated air passes through the treatment zone and is discharged into the environment.
The continuous rotational movement of the rotor displaces the adsorbent and its adsorbed organic-solvent vapor into the regeneration zone. A second air-blowing means supplies regenerating heated air to the regeneration zone, heating the adsorbent and removing organic-solvent vapor therefrom.
The continuous rotational movement of the rotor then rotates the heated adsorbent into the purge zone. The adsorbent is cooled by purge air that is supplied to the purge zone. As the purge air exits the purge zone, it joins with a stream of outside air. The purge air and outside air in combination pass through an air heater located on the inlet side of the second air-blowing means and thereafter form the regeneration air.
The apparatus provided by the present invention differs from that of the above-mentioned conventional apparatus in that a third wedge-shaped purge zone is positioned intermediate the regeneration zone and the treatment zone. Further, part of the regenerating heated air is preliminarily utilized as purged air, where it is heated by the rotor and adsorbent as it passes through the purge zone.
By passing purge air through the purge zone, the temperature of the adsorbent within the rotor is decreased before it re-enters the treatment zone. Because the adsorbent entering the treatment zone is cool, the adsorbent displays a greater adsorbing capability as it enters the treatment zone. The solvent-adsorbing efficiency of the apparatus is thereby enhanced and the size of the purge zone is minimized.